Advection of baroclinic eddies by depth mean flow

Observed zonal propagation speeds of nonlinear eddies, derived using an eddy tracking algorithm, are compared with the classical long Rossby wave speed, Doppler shifted by just the depth mean velocity, the latter obtained from annual mean hydrography and an ocean atlas. Despite neglecting any Doppler shift from baroclinic background flows, the correspondence between observed eddy propagation speeds and theoretical long Rossby wave phase speeds is improved in the Antarctic Circumpolar Current region, where both show eastward propagation at speeds of 1–3 cm s⁻¹, although the observed eastward eddy propagation speeds are systematically lower than the predicted Rossby wave phase speeds.